Field of the Invention
The invention relates to an auxiliary-pile carrier for a lifting device for a pile of sheets with a main-pile lifting unit and an auxiliary-pile lifting unit in sheet-processing machines, particularly in sheet-fed printing presses, wherein auxiliary-pile-carrier elements are supported on a rear cross-member and are insertable in a rod-like manner into grooves of a pile board underneath an auxiliary pile and being aligned parallel to the grooves in a horizontal plane, wherein a forward cross-member is provided as a support for free ends of the inserted auxiliary-pile-carrier elements and wherein both cross-members are suspended from the auxiliary-pile lifting unit. The invention relates particularly to a pile changing device in the feeder of a sheet-fed rotary offset printing machine.
Auxiliary-pile carriers are known, mostly in the context of deliveries of sheet-fed printing machines. The prior art carriers are in the form of a rake. In order to effect a semi-automatic change of piles in non-stop operation, the sprockets of the rake are inserted into a gap between two sheets above the main pile counter to a transport direction of the sheets. In this way, an auxiliary pile is formed on the rake and the main pile can be changed. When in the inserted position, the rake rests on a forward and a rear cross-member of an auxiliary frame. The auxiliary frame is suspended by chains from an auxiliary-pile lifting unit. When the auxiliary pile is to be deposited on a pile board for a new main pile, the rake is withdrawn in the transport direction of the sheets and is stowed away in a location where it does not interfere with the operation of the printing press. Similar devices are also known in the art of pile feeders of sheet-fed rotary offset printing press.
A sheet feeder is known from German published patent application DE 39 31 710 for continuous-stream sheet feed in non-stop operation on an inclined feed table. An auxiliary-pile carrier is formed by non-stop rods, which are inserted in the sheet transport direction into grooves formed on the upper surface of a pile board. The non-stop rods are individually connected to the piston of a pneumatic cylinder. The pneumatic cylinder is disposed behind the pile and underneath the feed table with its axis parallel to the feed table in the feeder. In this way, the non-stop rods are inserted and retracted by the force of a motor.
Finally, very elaborate devices are known for the fully automatic changing of the feeder pile in machines with automatic sheet-pile feeding which operate according to different technical principles.